Due to the rapid development of information industries, the kinds of peripheral devices therefore increase. Scanners, owing to their low price and convenience, are favored by PC users.
Generally speaking, the way a hand-held scanner is used is to move the scanner with hand on a scanned article. When the scanner smoothly passes through the article from one end to the other, a scanning operation is achieved. However, when the scanner is not moved under a certain condition, such as a constant scanning direction or an almost steady scanning speed, the quality of the scanning is affected. For example, if the direction of the scanning is slanted, the scanning result will possibly be distorted; and if the velocity is not accurately controlled, a line-drop situation will possibly occur.
In order to improve the scanning quality, a first kind of feeder used with a scanner was offered. This kind of feeder mounts therein two driven rollers and the scanner mounts therein two rollers, two springs and a motor. When the two rollers mounted in the bottom of the scanner are driven by the motor, the two driven rollers of the feeder are driven. Thus the scanned article can pass through the passage between the scanner rollers and the driven rollers. The function of the two springs urging respectively against the two scanner rollers is to adjust the distance between the scanner rollers and the driven rollers and assure that the scanned article thicker or thinner than the passage is fed successfully.
Although this kind of feeder allows articles of various thicknesses to be fed, it can be used only with a scanner with driving elements including the motor and scanner rollers. However, most of the early scanners have no driving element therein, and therefore this kind of feeder cannot satisfy the user having only an early scanner.
A second kind of feeder was therefore offered. A motor, driving rollers, driving belts and gears, and springs are mounted directly in a shell of this kind of feeder. The motor is used to drive the driving rollers by the aid of the driving belts and gears. The springs are used to adjust the distance between the rollers and the driven rollers and assure that the scanned article thicker or thinner than the passage is fed successfully.
Although this kind of feeder can be used with a scanner without a driving element therein, that the driving elements of this kind of feeder are directly mounted in the shell makes the mould for molding this kind of feeder and thus the feeder structure more complicated, which assumes a risk of scrapping the whole feeder if any part of the feeder structure has a little defect. Besides, that a performance test may proceed only after the whole feeder is set up completely results in the inflexibility of the working procedure. Furthermore, due to various aesthetic senses recognized in different countries, the shells are often required to have various appearances. If the driving elements are to be manufactured together with the various kinds of shells of various appearances, various kinds of complicated feeder moulds are needed and thus the cost spent for various feeder moulds is too much.